First Battle of the Marne

The First Battle of the Marne was fought from 6 to 12 September 1914 when the combined armies of France and Britain halted the German advance on Paris at the River Marne during World War I. The French and British offensive forced the Germans to withdraw, and the Germans were forced to retreat for 65 miles, with the Entente forces pursuing them. It was there that the Germans dug trenches and fortified their positions, inaugurating four years of trench warfare.

Background
Up to the first week of September, when the Battle of the Marne began, the war had brought a remarkable series of German victories on both the Eastern and Western fronts. French offensives were thrown back in Lorraine and the Ardennes. Driven out of Belgium, the French 5th Army and the BEF were pursued by German armies and forced to retreat beyond the Marne River. This rapid German advance, however, left the flank of the German 1st Army exposed to a counterattack by General Joseph Gallieni's forces around Paris.

Battle
The Battle fo the Marne opened prematurely. General Joseph Joffre ordered the Allied counteroffensive to begin on 6 September. In preparation, on 5 September, the eager General Gallieni, commanding in Paris, moved General Michel-Joseph Maunoury's French 6th Army forward toward the exposed flank of the German First Army.

Strengths and weaknesses
The Germans' main strength had advanced to the south, leaving only a reserve corps under General Hans von Gronau defending the flank. Spotting the French advance, Gronau boldly opted to attack, exploiting the advantage of high ground. Soon, an already familiar spectacle was being repeated: French troops in their bright uniforms, poorly supported by artillery, cut down in swathes by superior German firepower. The German 1st Army commander, General Alexander von Kluck, responded to the outbreak of fighting by skilfully shifting troops back to confront the threat.

The French Sixth Army was a hastily assembled formation, chiefly consisting of reserves and Moroccan troops. Facing the increasing weight of Kluck's forces, it was soon experiencing severe difficulties. Despite Gallieni's commandeering of Parisian taxis and buses to rush troops to the front - the French army had almost no motor transportation - by 8 September, Kluck was threatening Paris.

Nonetheless, the strategic situation was shifting in favor of the Allies. While the French 9th Army under Ferdinand Foch fought a desperate holding action in the Gond marshels, General Louis Franchet d'Esperey led his Fifth Army forward against General Karl von Bulow's German 2nd Army. The Allies were short of supplies and exhausted by weeks of marching, but after tough fighting it was the Germans who fell back.

Lost opportunity
Meanwhile, Franchet d'Esperey fumed at the tardiness of the British on his left. Field Marshal Sir John French, who had been persuaded with some difficulty to promise Joffre his cooperation, was asked to advance into a gap that had opened between the German First and Second Armies. He did so, but with excessive caution and a distinct lack of urgency. To the French commanders, it seemed that a chance to impose a decisive defeat on the Germans was being lost.

The German Chief of the General Staff Helmuth von Moltke, at his headquarters in Luxembourg, was a worried man. Unclear about the state of the fighting, he sent a staff intelligence officer, Lieutenant Colonel Richard Hentsch, to visit each of the army headquarters in turn. After discussing the situation with Bulow, Hensch judged that a German withdrawal was urgently needed. On 9 September, Bulow began to disengage his forces, while Hentsch passed on the news to Kluck. Although the German 1st Army was winning its part of the battle, Kluck had no choice but to pull back his troops along with Bulow.

Last act
Belatedly intervening in a situation that had slipped beyond his control, Moltke set the Aisne River as the line to which the armies would withdraw. It was his last act as Chief of Staff. Having failed to implement the Schlieffen Plan, he was dismissed. Joffre, the architect of the "miracle of the Marne", was hailed as the savior of France.

Aftermath
The retreating Germans dug into a strng defensive position on the Aisne, where they halted the Allied counteroffensive on 12 September. The successful German defense on the Aisne initiated static trench warfare - the rival armies were still fighting over the same ground in spring 1918. Elsewhere on the Western Front, mobile warfare continued until November 1914, with the outflanking movements of the "Race to the Sea" culminating in the First Battle of Ypres.

Two million men took part in the Battle of the Marne. By the end, a quarter of these had been killed, or were wounded or missing. Many of the battle sites would be fought over again in the Second Battle of the Marne in July-August 1918.